Exocyclic amine substituted coumarin compounds and uses as fluorescent labels

ABSTRACT

The present application relates to exocyclic amine-substituted coumarin derivatives and their uses as fluorescent labels. These compounds may be used as fluorescent labels for nucleotides in nucleic acid sequencing applications.

INCORPORATION BY REFERENCE TO PRIORITY APPLICATION

The present application claims the benefit of priority to U.S.Provisional Application No. 62/812,837, filed Mar. 1, 2019, which isincorporated by reference in its entirety.

FIELD

The present disclosure relates to exocyclic amine-substituted coumarinderivatives and their uses as fluorescent markers. In particular, thecompounds may be used as fluorescent labels for nucleotides in nucleicacid sequencing applications.

BACKGROUND

Several publications and patent documents are referenced in thisapplication to more fully describe the state of the art to which thisdisclosure pertains. The disclosure of each of these publications anddocuments is incorporated by reference herein.

Non-radioactive detection of nucleic acids bearing fluorescent labels isan important technology in molecular biology. Many procedures employedin recombinant DNA technology previously relied on the use ofnucleotides or polynucleotides radioactively labeled with, for example³²P. Radioactive compounds permit sensitive detection of nucleic acidsand other molecules of interest. However, there are serious limitationsin the use of radioactive isotopes such as their expense, limited shelflife, insufficient sensitivity, and, more importantly, safetyconsiderations. Eliminating the need for radioactive labels reduces boththe safety risks and the environmental impact and costs associated with,for example, reagent disposal. Methods amenable to non-radioactivefluorescent detection include by way of non-limiting examples, automatedDNA sequencing, hybridization methods, real-time detection ofpolymerase-chain-reaction products, and immunoassays.

For many applications, it is desirable to employ multiplespectrally-distinguishable fluorescent labels to achieve independentdetection of a plurality of spatially-overlapping analytes. In suchmultiplex methods, the number of reaction vessels may be reduced,simplifying experimental protocols and facilitating the production ofapplication-specific reagent kits. In multi-color automated DNAsequencing systems for example, multiplex fluorescent detection allowsfor the analysis of multiple nucleotide bases in a singleelectrophoresis lane, thereby increasing throughput over single-colormethods, and reducing uncertainties associated with inter-laneelectrophoretic mobility variations.

However, multiplex fluorescent detection can be problematic and thereare a number of important factors that constrain selection ofappropriate fluorescent labels. First, it may be difficult to find dyecompounds with suitably-resolved absorption and emission spectra in agiven application. In addition, when several fluorescent dyes are usedtogether, generating fluorescence signals in distinguishable spectralregions by simultaneous excitation may be complicated because absorptionbands of the dyes are usually widely separated, so it is difficult toachieve comparable fluorescence excitation efficiencies even for twodyes. Many excitation methods use high power light sources like lasersand therefore the dye must have sufficient photo-stability to withstandsuch excitation. A final consideration of particular importance tomolecular biology methods is the extent to which the fluorescent dyesmust be compatible with reagent chemistries such as, for example, DNAsynthesis solvents and reagents, buffers, polymerase enzymes, and ligaseenzymes.

As sequencing technology advances, a need has developed for furtherfluorescent dye compounds, their nucleic acid conjugates, and multipledye sets that satisfy all the above constraints and that are amenableparticularly to high throughput molecular methods such as solid phasesequencing and the like.

Fluorescent dye molecules with improved fluorescence properties such assuitable fluorescence intensity, shape, and wavelength maximum offluorescence can improve the speed and accuracy of nucleic acidsequencing. Strong fluorescence signals are especially important whenmeasurements are made in water-based biological buffers and at highertemperatures as the fluorescence intensities of most dyes aresignificantly lower under such conditions. Moreover, the nature of thebase to which a dye is attached also affects the fluorescence maximum,fluorescence intensity, and others spectral dye properties. Thesequence-specific interactions between the nucleobases and thefluorescent dyes can be tailored by specific design of the fluorescentdyes. Optimization of the structure of the fluorescent dyes can improvethe efficiency of nucleotide incorporation, reduce the level ofsequencing errors, and decrease the usage of reagents in, and thereforethe costs of, nucleic acid sequencing.

Some optical and technical developments have already led to greatlyimproved image quality but were ultimately limited by poor opticalresolution. Generally, optical resolution of light microscopy is limitedto objects spaced at approximately half of the wavelength of the lightused. In practical terms, then, only objects that are laying quite farapart (at least 200 to 350 nm) could be resolved by light microscopy.One way to improve image resolution and increase the number ofresolvable objects per unit of surface area is to use excitation lightof a shorter wavelength. For example, if light wavelength is shortenedby Δλ˜100 nm with the same optics, resolution will be better (about Δ50nm/(about 15%)), less-distorted images will be recorded, and the densityof objects on the recognizable area will be increased about 35%.

Certain nucleic acid sequencing methods employ laser light to excite anddetect dye-labeled nucleotides. These instruments use longer wavelengthlight, such as red lasers, along with appropriate dyes that areexcitable at 660 nm. To detect more densely packed nucleic acidsequencing clusters while maintaining useful resolution, a shorterwavelength blue light source (450-460 nm) may be used. In this case,optical resolution will be limited not by the emission wavelength of thelonger wavelength red fluorescent dyes but rather by the emission ofdyes excitable by the next longest wavelength light source, for example,by “green laser” at 532 nm. Thus, there is a need for blue dye labelsfor use in fluorescence detection in sequencing applications.

Although blue-dye chemistry and associated laser technologies haveimproved, for example, to yield dyes for DVD and Blu-ray disks, thesecompounds are not appropriate for bio-labeling and cannot be used asbiomarkers.

Unfortunately, commercially available blue dyes with strong fluorescencesuitable for nucleotide labeling are still quite rare. Described hereinare new fluorescent compounds suitable for nucleotide labeling withstrong fluorescence under blue light excitation.

SUMMARY

The present disclosure relates to exocyclic amine-substituted coumarinderivatives. The compounds may be useful as fluorescent labels,particularly for nucleotide labeling in nucleic acid sequencingapplications. In some aspects, the dyes absorb light at short-wavelengthlight, optimally at a wavelength of 450-460 nm and are particularlyadvantageous in situations where blue wavelength excitation sourceshaving a wavelength of 450-460 nm are used. Blue wavelength excitationallows detection and resolution of a higher density of features per unitarea due to the shorter wavelength of fluorescence emission. When suchdyes are used in conjugates with nucleotides, improvements can be seenin the length, intensity, accuracy, and quality of sequencing readsobtained during nucleic acid sequencing methods.

Some embodiments of the present disclosure relate to a compound ofFormula (I), or a salt thereof:

wherein X is O, S, Se, or NR^(n), wherein R^(n) is H, C₁₋₆ alkyl orC₆₋₁₀ aryl;

ring A is a 3 to 10 membered heterocyclyl;

R, R¹, R², and R⁴ are each independently H, halo, —CN, —CO₂H, amino,—OH, C-amido, N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b), optionallysubstituted alkyl, optionally substituted alkenyl, optionallysubstituted alkynyl, optionally substituted alkoxy, optionallysubstituted aminoalkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl;

each R³ is independently halo, —CN, —CO₂H, —(CH₂)_(p)—CO₂R^(c),—(CH₂)_(q)—C(O)NR^(d)R^(e), amino, —OH, C-amido, N-amido, —NO₂, —SO₃H,—SO₂NR^(a)R^(b), optionally substituted C₁₋₆ alkyl, optionallysubstituted C₂₋₆ alkenyl, optionally substituted C₂₋₆ alkynyl,optionally substituted carbocyclyl, optionally substituted heterocyclyl,optionally substituted aryl, or optionally substituted heteroaryl, ortwo R³ form oxo (═O); wherein p and q are each 1, 2, 3 or 4;

each R⁵ is independently halo, —CN, —CO₂R^(f), amino, —OH, C-amido,N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b), optionally substituted alkyl,optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted alkoxy, optionally substituted aminoalkyl,optionally substituted carbocyclyl, optionally substituted heterocyclyl,optionally substituted aryl, or optionally substituted heteroaryl;

each R^(a) and R^(b) is independently H or optionally substituted C₁₋₆alkyl;

each R^(c), R^(d), R^(e) and R^(f) is independently H, optionallysubstituted C₁₋₆ alkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl;

m is 0, 1, 2, 3, or 4; and n is 0, 1, 2, 3, 4 or 5.

In some aspects, at least one of m or n is not 0. In some furtheraspects, when each of R, R¹, R², and R⁴ is H, then at least one of mornis not 0. For example, when each of R, R¹, R², and R⁴ is H, m is 0, thenn is 1, 2, 3, 4, or 5. When each of R, R¹, R², and R⁴ is H, n is 0, thenm is 1, 2, 3, or 4. In some aspects, when m is 1; R⁵ is —CO₂H; each ofR, R¹, R², R⁴ is H; ring A is

then X is O, Se, or NR^(n).

In some other embodiments, a compound of the present disclosure isconjugated with a substrate moiety such as, for example, a nucleoside,nucleotide, polynucleotide, polypeptide, carbohydrate, ligand, particle,cell, semi-solid surface (e.g., gel), or solid surface. The conjugationmay be carried out via a carboxyl group (—CO₂H), which can be reactedusing methods known in the art with an amino or hydroxyl group on amoiety (such as a nucleotide) or a linker bound thereto, to form anamide or ester.

Some other aspects of the present disclosure relate to dye compoundscomprising linker groups to enable, for example, covalent attachment toa substrate moiety. Linking may be carried out at any position of thedye, including at any of the R groups. In some embodiments, linking maybe carried out via R³ or via R⁵ of Formula (I).

Some further aspects of the present disclosure provide a nucleoside ornucleotide compound defined by the formula:N-L-Dye

wherein N is a nucleotide;

L is an optional linker moiety; and

Dye is a fluorescent compound according to the present disclosure.

Some additional embodiments described herein are related to a moiety, inparticular nucleotide or oligonucleotide, labeled with a compound ofFormula (I).

Some additional disclosure provides methods of sequencing using the dyecompounds of the present disclosure.

According to a further aspect the disclosure also provides a kitcomprising a dye compound (free or in conjugate form) that may be usedin various immunological assays, oligonucleotide or nucleic acidlabeling, or for DNA sequencing by synthesis. In yet another aspect, thedisclosure provides kits comprising dye “sets” particularly suited tocycles of sequencing by synthesis on an automated instrument platform.In some aspects are kits containing one or more nucleotides where atleast one nucleotide is a labeled nucleotide described herein.

A further aspect of the disclosure is the chemical preparation ofcompounds of the disclosure, including exocyclic amine-substitutedcoumarin dyes and moieties such as nucleotides labeled with such dyes.

In further aspects are methods of sequencing including incorporating alabeled nucleotide described herein in a polynucleotide in a sequencingassay, and detecting the incorporated, labeled nucleotide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scatterplot illustrating the usability of a fullyfunctionalized A nucleotide labeled with dye 1-4 described herein in atwo-channel sequencing analysis.

FIG. 2 is a scatterplot illustrating the usability of a fullyfunctionalized A nucleotide labeled with dye 1-5 described herein in atwo-channel sequencing analysis.

FIG. 3 is a scatterplot illustrating the usability of a fullyfunctionalized A nucleotide labeled with dye 1-6 described herein in atwo-channel sequencing analysis.

DETAILED DESCRIPTION

The present disclosure provides exocyclic amine-substituted coumarincompounds particularly suitable for methods of fluorescence detectionand sequencing by synthesis. Embodiments described herein relate to dyesand their derivatives of the structure of Formula (I), salts andmesomeric forms thereof.

In some aspects, X is O. In some aspects, X is S. In some aspects, X isSe. In some aspects, X is NR^(n), wherein R^(n) is H, C₁₋₆ alkyl, orC₆₋₁₀ aryl, and in one aspect, R^(n) is H. In some further embodiments,when m is 1; R⁵ is —CO₂H; each of R, R¹, R², R⁴ is H; ring A is

then X is O, Se, or NR^(n). In some further embodiments, when n is 0;ring A is

each of R, R¹, R², R⁴ is H; X is O; then m is 1, 2, 3, or 4. In someaspects, when n is 0, then m is 1, 2, 3, or 4 and at least one R⁵ is—CO₂H. In some other aspects, when n is 1 and R³ is —CO₂H, then m is 0or R⁵ is not —CO₂H.

In some aspects, R is H, halo, —CO₂H, amino, —OH, C-amido, N-amido,—NO₂, —SO₃H, —SO₂NH₂, optionally substituted alkyl, optionallysubstituted alkenyl, optionally substituted alkynyl, optionallysubstituted alkoxy, optionally substituted aminoalkyl, optionallysubstituted carbocyclyl, optionally substituted heterocyclyl, optionallysubstituted aryl, or optionally substituted heteroaryl. In one aspect, Ris H. In another aspect, R is halo. In some aspects, R is optionallysubstituted C₁₋₆ alkyl. In some aspects, R is —CO₂H. In some aspects, Ris —SO₃H. In some aspects, R is —SO₂NR^(a)R^(b), wherein R^(a) and R^(b)is independently H or optionally substituted C₁₋₆ alkyl. In one aspect,R is —SO₂NH₂. In some aspect, R is not —CN.

In some aspects, R¹ is H. In some aspects, R¹ is halo. In some aspects,R¹ is —CN. In some aspects, R¹ is C₁₋₆ alkyl. In some aspects, R¹ is—SO₂NR^(a)R^(b), wherein R^(a) and R^(b) is independently H oroptionally substituted C₁₋₆ alkyl. In one aspect, R¹ is —SO₂NH₂. In someaspect, R¹ is not —CN.

In some aspects, R² is H. In some aspects, R² is halo. In some aspect,R² is —SO₃H. In some aspects, R² is optionally substituted alkyl, forexample C₁₋₆ alkyl. In some further embodiments, R² is C₁₋₄ alkyloptionally substituted with —CO₂H or —SO₃H.

In some aspects, R⁴ is H. In some aspects, R⁴ is —SO₃H. In some aspects,R⁴ is optionally substituted alkyl, for example C₁₋₆ alkyl. In somefurther embodiments, R⁴ is C₁₋₄ alkyl optionally substituted with —CO₂Hor —SO₃H.

In some aspects, ring A is a 3 to 7 membered single heterocyclic ring.In some further embodiments, the 3 to 7 membered single heterocyclicring contains one or more heteroatoms selected from the group consistingof nitrogen, oxygen, and sulfur. In some further embodiments, the 3 to 7membered single heterocyclic ring contains one nitrogen atom. In someaspects, ring A is

In one such embodiment, ring A is

In some aspects, ring A is

In one such embodiment, ring A is

In some aspects, ring A is

In one such embodiment, ring A is

In some aspects of the ring A described herein, n is 0. In some aspectsof the ring A described herein, n is 1. In some aspects of the ring Adescribed herein, n is 2 or 3. In some aspects, each R³ is independently—CO₂H, —SO₃H, C₁₋₄ alkyl optionally substituted with —CO₂H or —SO₃H,—(CH₂)_(p)—CO₂R^(c), or optionally substituted C₁₋₆ alkyl. In someaspects, R³ is methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, pentyl, or hexyl. In other aspects, R³ issubstituted C₁₋₄ alkyl. In some aspects, R³ is C₁₋₄ alkyl or C₂₋₆ alkylsubstituted with —CO₂H or —SO₃H. In some further embodiments, n is 1 andR³ is —CO₂H or —(CH₂)_(p)—CO₂R^(c). In some further embodiments, R^(c)is H or C₁₋₄ alkyl.

The benzene ring of the

moiety of Formula (I) is optionally substituted in any one, two, three,or four positions by a substituent shown as R⁵. Where m is zero, thebenzene ring is unsubstituted. Where m is greater than 1, each R⁵ may bethe same or different. In some aspects, m is 0. In other aspects, mis 1. In other aspects, m is 2. In some aspects, m is 1, 2, or 3, andeach R⁵ is independently halo, —CN, —CO₂R^(f), amino, —OH, —SO₃H,—SO₂NR^(a)R^(b) or optionally substituted C₁₋₆ alkyl, where R^(f) is Hor C₁₋₄ alkyl. In some further embodiments, R⁵ is —CO₂H, —SO₃H, —SO₂NH₂,or C₁₋₆ alkyl substituted with —CO₂H, —SO₃H, or —SO₂NH₂. In some furtherembodiments, R⁵ is —(CH₂)_(x)COOH where x is 2, 3, 4, 5 or 6. In someembodiments, when each of R, R¹, R², R⁴ is H; n is 0; m is 1; then

is substituted at the following position:

In one embodiment, R⁵ is —CO₂H.

Particular examples of a compound of Formula (I) include where X is O, Sor NH; each R, R¹, R², and R⁴ is H; ring A is

n is 0 or 1; R³ is —CO₂H or —(CH₂)_(p)—CO₂R^(c); p is 1, 2, 3, or 4;R^(c) is H or C₁₋₆ alkyl; m is 0 or 1; and R⁵ is halo, —CO₂R^(f), —SO₃H,—SO₂NR^(a)R^(b), or C₁₋₆ alkyl substituted with —SO₃H or—SO₂NR^(a)R^(b). In some embodiments, at least one or both of R^(a) andR^(b) is H or C₁₋₆ alkyl. In some further embodiments, R^(f) is H orC₁₋₄ alkyl. In some further embodiments, when m is 0, then n is 1; orwhen n is 0, then m is 1. In one embodiment, both m and n are 1. In somefurther embodiments, when m is 1,

is at substituted at the following position:

In one embodiment, R⁵ is —CO₂H. In another embodiment, R⁵ is halo, suchas chloro, or —SO₃H. In yet another embodiment, R⁵ is —SO₂NR^(a)R^(b)where at least one or both of R^(a) and R^(b) is H or C₁₋₆ alkyl.

Particular examples of a compound of Formula (I) include where X is O, Sor NH; each R, R¹, R², and R⁴ is H; ring A is

n is 0 or 1; R³ is —CO₂H or —(CH₂)_(p)—CO₂R^(c); p is 1, 2, 3, or 4;R^(c) is H or C₁₋₆ alkyl; m is 0 or 1; and R⁵ is halo, —CO₂R^(f), —SO₃H,—SO₂NR^(a)R^(b), or C₁₋₆ alkyl substituted with —SO₃H or—SO₂NR^(a)R^(b). In some embodiments, at least one or both of R^(a) andR^(b) is H or C₁₋₆ alkyl. In some further embodiments, R^(f) is H orC₁₋₄ alkyl. In some further embodiments, when m is 0, then n is 1; orwhen n is 0, then m is 1. In one embodiment, both m and n are 1. In somefurther embodiments, when m is 1,

is at substituted at the following position:

In one embodiment, R⁵ is —CO₂H. In another embodiment, R⁵ is halo, suchas chloro, or —SO₃H. In yet another embodiment, R⁵ is —SO₂NR^(a)R^(b)where at least one or both of R^(a) and R^(b) is H or C₁₋₆ alkyl.

Particular examples of a compound of Formula (I) include where X is O, Sor NH; each R, R¹, R², and R⁴ is H; ring A is

n is 0 or 1; R³ is —CO₂H or —(CH₂)_(p)—CO₂R^(c); p is 1, 2, 3, or 4;R^(c) is H or C₁₋₆ alkyl; m is 0 or 1; and R⁵ is halo, —CO₂R^(f), —SO₃H,—SO₂NR^(a)R^(b), or C₁₋₆ alkyl substituted with —SO₃H or—SO₂NR^(a)R^(b). In some embodiments, at least one or both of R^(a) andR^(b) is H or C₁₋₆ alkyl. In some further embodiments, R^(f) is H orC₁₋₄ alkyl. In some further embodiments, when m is 0, then n is 1; orwhen n is 0, then m is 1. In one embodiment, both m and n are 1. In somefurther embodiments, when m is 1,

is at substituted at the following position:

In one embodiment, R⁵ is —CO₂H. In another embodiment, R⁵ is halo, suchas chloro, or —SO₃H. In yet another embodiment, R⁵ is —SO₂NR^(a)R^(b)where at least one or both of R^(a) and R^(b) is H or C₁₋₆ alkyl.

Specific examples of exocyclic amine-substituted coumarin dyes include:

and salts and mesomeric forms thereof.

A particularly useful compound is a nucleotide or oligonucleotidelabeled with a dye as described herein. The labeled nucleotide oroligonucleotide may be attached to the dye compound disclosed herein viaa carboxy or an alkyl-carboxy group to form an amide or alkyl-amide. Forexample, the dye compound disclosed herein is attached the nucleotide oroligonucleotide via R³ or R⁵ of Formula (I). In some embodiments, R³ ofFormula (I) is —CO₂H or —(CH₂)_(p)—CO₂H and the attachment forms anamide using the —CO₂H group. In some embodiments, R⁵ of Formula (I) is—CO₂H and the attachment forms an amide using the —CO₂H group. Thelabeled nucleotide or oligonucleotide may have the label attached to theC₅ position of a pyrimidine base or the C7 position of a 7-deaza purinebase through a linker moiety.

The labeled nucleotide or oligonucleotide may also have a blocking groupcovalently attached to the ribose or deoxyribose sugar of thenucleotide. The blocking group may be attached at any position on theribose or deoxyribose sugar. In particular embodiments, the blockinggroup is at the 3′ OH position of the ribose or deoxyribose sugar of thenucleotide.

Provided herein are kits including two or more nucleotides wherein atleast one nucleotide is a nucleotide labeled with a compound of thepresent disclosure. The kit may include two or more labeled nucleotides.The nucleotides may be labeled with two or more fluorescent labels. Twoor more of the labels may be excited using a single excitation source,which may be a laser. For example, the excitation bands for the two ormore labels may be at least partially overlapping such that excitationin the overlap region of the spectrum causes both labels to emitfluorescence. In particular embodiments, the emission from the two ormore labels will occur in different regions of the spectrum such thatpresence of at least one of the labels can be determined by opticallydistinguishing the emission.

The kit may contain four labeled nucleotides, where the first of fournucleotides is labeled with a compound as disclosed herein. In such akit, each of the four nucleotides can be labeled with a compound that isthe same or different from the label on the other three nucleotides.Thus, one or more of the compounds can have a distinct absorbancemaximum and/or emission maximum such that the compound(s) is(are)distinguishable from other compounds. For example, each compound canhave a distinct absorbance maximum and/or emission maximum such thateach of the compounds is distinguishable from the other three compounds.It will be understood that parts of the absorbance spectrum and/oremission spectrum other than the maxima can differ and these differencescan be exploited to distinguish the compounds. The kit may be such thattwo or more of the compounds have a distinct absorbance maximum. Thecompounds of the invention typically absorb light in the region below500 nm.

The compounds, nucleotides, or kits that are set forth herein may beused to detect, measure, or identify a biological system (including, forexample, processes or components thereof). Exemplary techniques that canemploy the compounds, nucleotides or kits include sequencing, expressionanalysis, hybridization analysis, genetic analysis, RNA analysis,cellular assay (e.g., cell binding or cell function analysis), orprotein assay (e.g., protein binding assay or protein activity assay).The use may be on an automated instrument for carrying out a particulartechnique, such as an automated sequencing instrument. The sequencinginstrument may contain two lasers operating at different wavelengths.

Disclosed herein are methods of synthesizing compounds of thedisclosure. Dyes according to the present disclosure may be synthesizedfrom a variety of different suitable starting materials. For example,compounds of Formula (I) may be prepared by reacting a compound ofFormula (II) with an optionally substituted cyclic amine of Formula(III):

where each of the variables, X, R, R¹, R², R³, R⁴, R⁵, ring A, m and nare defined herein. The reaction may be conducted in organic solvents atambient or elevated temperature.

Definitions

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.

It is noted that, as used in this specification and the appended claims,the singular forms “a”, “an” and “the” include plural referents unlessexpressly and unequivocally limited to one referent. It will be apparentto those skilled in the art that various modifications and variationscan be made to various embodiments described herein without departingfrom the spirit or scope of the present teachings. Thus, it is intendedthat the various embodiments described herein cover other modificationsand variations within the scope of the appended claims and theirequivalents.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art. The use of the term “including” as well as other forms, suchas “include”, “includes,” and “included,” is not limiting. The use ofthe term “having” as well as other forms, such as “have”, “has,” and“had,” is not limiting. As used in this specification, whether in atransitional phrase or in the body of the claim, the terms “comprise(s)”and “comprising” are to be interpreted as having an open-ended meaning.That is, the above terms are to be interpreted synonymously with thephrases “having at least” or “including at least.” For example, whenused in the context of a process, the term “comprising” means that theprocess includes at least the recited steps but may include additionalsteps. When used in the context of a compound, composition, or device,the term “comprising” means that the compound, composition, or deviceincludes at least the recited features or components, but may alsoinclude additional features or components.

As used herein, the term “covalently attached” or “covalently bonded”refers to the forming of a chemical bonding that is characterized by thesharing of pairs of electrons between atoms. For example, a covalentlyattached polymer coating refers to a polymer coating that forms chemicalbonds with a functionalized surface of a substrate, as compared toattachment to the surface via other means, for example, adhesion orelectrostatic interaction. It will be appreciated that polymers that areattached covalently to a surface can also be bonded via means inaddition to covalent attachment.

The term “halogen” or “halo,” as used herein, means any one of theradio-stable atoms of column 7 of the Periodic Table of the Elements,e.g., fluorine, chlorine, bromine, or iodine, with fluorine and chlorinebeing preferred.

As used herein, “alkyl” refers to a straight or branched hydrocarbonchain that is fully saturated (i.e., contains no double or triplebonds). The alkyl group may have 1 to 20 carbon atoms (whenever itappears herein, a numerical range such as “1 to 20” refers to eachinteger in the given range; e.g., “1 to 20 carbon atoms” means that thealkyl group may consist of 1 carbon atom, 2 carbon atoms, 3 carbonatoms, etc., up to and including 20 carbon atoms, although the presentdefinition also covers the occurrence of the term “alkyl” where nonumerical range is designated). The alkyl group may also be a mediumsize alkyl having 1 to 9 carbon atoms. The alkyl group could also be alower alkyl having 1 to 6 carbon atoms. The alkyl group may bedesignated as “C₁₋₄ alkyl” or similar designations. By way of exampleonly, “C₁₋₆ alkyl” indicates that there are one to six carbon atoms inthe alkyl chain, i.e., the alkyl chain is selected from the groupconsisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl,sec-butyl, and t-butyl. Typical alkyl groups include, but are in no waylimited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiarybutyl, pentyl, hexyl, and the like.

As used herein, “alkoxy” refers to the formula —OR wherein R is an alkylas is defined above, such as “C₁₋₉ alkoxy”, including but not limited tomethoxy, ethoxy, n-propoxy, 1-methylethoxy (isopropoxy), n-butoxy,iso-butoxy, sec-butoxy, and tert-butoxy, and the like.

As used herein, “alkenyl” refers to a straight or branched hydrocarbonchain containing one or more double bonds. The alkenyl group may have 2to 20 carbon atoms, although the present definition also covers theoccurrence of the term “alkenyl” where no numerical range is designated.The alkenyl group may also be a medium size alkenyl having 2 to 9 carbonatoms. The alkenyl group could also be a lower alkenyl having 2 to 6carbon atoms. The alkenyl group may be designated as “C₂₋₆ alkenyl” orsimilar designations. By way of example only, “C₂₋₆ alkenyl” indicatesthat there are two to six carbon atoms in the alkenyl chain, i.e., thealkenyl chain is selected from the group consisting of ethenyl,propen-1-yl, propen-2-yl, propen-3-yl, buten-1-yl, buten-2-yl,buten-3-yl, buten-4-yl, 1-methyl-propen-1-yl, 2-methyl-propen-1-yl,1-ethyl-ethen-1-yl, 2-methyl-propen-3-yl, buta-1,3-dienyl,buta-1,2,-dienyl, and buta-1,2-dien-4-yl. Typical alkenyl groupsinclude, but are in no way limited to, ethenyl, propenyl, butenyl,pentenyl, and hexenyl, and the like.

As used herein, “alkynyl” refers to a straight or branched hydrocarbonchain containing one or more triple bonds. The alkynyl group may have 2to 20 carbon atoms, although the present definition also covers theoccurrence of the term “alkynyl” where no numerical range is designated.The alkynyl group may also be a medium size alkynyl having 2 to 9 carbonatoms. The alkynyl group could also be a lower alkynyl having 2 to 6carbon atoms. The alkynyl group may be designated as “C₂₋₆ alkynyl” orsimilar designations. By way of example only, “C₂₋₆ alkynyl” indicatesthat there are two to six carbon atoms in the alkynyl chain, i.e., thealkynyl chain is selected from the group consisting of ethynyl,propyn-1-yl, propyn-2-yl, butyn-1-yl, butyn-3-yl, butyn-4-yl, and2-butynyl. Typical alkynyl groups include, but are in no way limited to,ethynyl, propynyl, butynyl, pentynyl, and hexynyl, and the like.

As used herein, “heteroalkyl” refers to a straight or branchedhydrocarbon chain containing one or more heteroatoms, that is, anelement other than carbon, including but not limited to, nitrogen,oxygen and sulfur, in the chain backbone. The heteroalkyl group may have1 to 20 carbon atom, although the present definition also covers theoccurrence of the term “heteroalkyl” where no numerical range isdesignated. The heteroalkyl group may also be a medium size heteroalkylhaving 1 to 9 carbon atoms. The heteroalkyl group could also be a lowerheteroalkyl having 1 to 6 carbon atoms. The heteroalkyl group may bedesignated as “C₁₋₆ heteroalkyl” or similar designations. Theheteroalkyl group may contain one or more heteroatoms. By way of exampleonly, “C₄₋₆ heteroalkyl” indicates that there are four to six carbonatoms in the heteroalkyl chain and additionally one or more heteroatomsin the backbone of the chain.

The term “aromatic” refers to a ring or ring system having a conjugatedpi electron system and includes both carbocyclic aromatic (e.g., phenyl)and heterocyclic aromatic groups (e.g., pyridine). The term includesmonocyclic or fused-ring polycyclic (i.e., rings which share adjacentpairs of atoms) groups provided that the entire ring system is aromatic.

As used herein, “aryl” refers to an aromatic ring or ring system (i.e.,two or more fused rings that share two adjacent carbon atoms) containingonly carbon in the ring backbone. When the aryl is a ring system, everyring in the system is aromatic. The aryl group may have 6 to 18 carbonatoms, although the present definition also covers the occurrence of theterm “aryl” where no numerical range is designated. In some embodiments,the aryl group has 6 to 10 carbon atoms. The aryl group may bedesignated as “C₆₋₁₀ aryl,” “C₆ or C₁₀ aryl,” or similar designations.Examples of aryl groups include, but are not limited to, phenyl,naphthyl, azulenyl, and anthracenyl.

An “aralkyl” or “arylalkyl” is an aryl group connected, as asubstituent, via an alkylene group, such as “C₇₋₁₄ aralkyl” and thelike, including but not limited to benzyl, 2-phenylethyl,3-phenylpropyl, and naphthylalkyl. In some cases, the alkylene group isa lower alkylene group (i.e., a C₁₋₆ alkylene group).

As used herein, “heteroaryl” refers to an aromatic ring or ring system(i.e., two or more fused rings that share two adjacent atoms) thatcontain(s) one or more heteroatoms, that is, an element other thancarbon, including but not limited to, nitrogen, oxygen and sulfur, inthe ring backbone. When the heteroaryl is a ring system, every ring inthe system is aromatic. The heteroaryl group may have 5-18 ring members(i.e., the number of atoms making up the ring backbone, including carbonatoms and heteroatoms), although the present definition also covers theoccurrence of the term “heteroaryl” where no numerical range isdesignated. In some embodiments, the heteroaryl group has 5 to 10 ringmembers or 5 to 7 ring members. The heteroaryl group may be designatedas “5-7 membered heteroaryl,” “5-10 membered heteroaryl,” or similardesignations. Examples of heteroaryl rings include, but are not limitedto, furyl, thienyl, phthalazinyl, pyrrolyl, oxazolyl, thiazolyl,imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, triazolyl,thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl,quinolinyl, isoquinlinyl, benzimidazolyl, benzoxazolyl, benzothiazolyl,indolyl, isoindolyl, and benzothienyl.

A “heteroaralkyl” or “heteroarylalkyl” is heteroaryl group connected, asa substituent, via an alkylene group. Examples include but are notlimited to 2-thienylmethyl, 3-thienylmethyl, furylmethyl, thienylethyl,pyrrolylalkyl, pyridylalkyl, isoxazollylalkyl, and imidazolylalkyl. Insome cases, the alkylene group is a lower alkylene group (i.e., a C₁₋₆alkylene group).

As used herein, “carbocyclyl” means a non-aromatic cyclic ring or ringsystem containing only carbon atoms in the ring system backbone. Whenthe carbocyclyl is a ring system, two or more rings may be joinedtogether in a fused, bridged or spiro-connected fashion. Carbocyclylsmay have any degree of saturation provided that at least one ring in aring system is not aromatic. Thus, carbocyclyls include cycloalkyls,cycloalkenyls, and cycloalkynyls. The carbocyclyl group may have 3 to 20carbon atoms, although the present definition also covers the occurrenceof the term “carbocyclyl” where no numerical range is designated. Thecarbocyclyl group may also be a medium size carbocyclyl having 3 to 10carbon atoms. The carbocyclyl group could also be a carbocyclyl having 3to 6 carbon atoms. The carbocyclyl group may be designated as “C₃₋₆carbocyclyl” or similar designations. Examples of carbocyclyl ringsinclude, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cyclohexenyl, 2,3-dihydro-indene, bicycle[2.2.2]octanyl,adamantyl, and spiro[4.4]nonanyl.

As used herein, “cycloalkyl” means a fully saturated carbocyclyl ring orring system. Examples include cyclopropyl, cyclobutyl, cyclopentyl, andcyclohexyl.

As used herein, “heterocyclyl” means a non-aromatic cyclic ring or ringsystem containing at least one heteroatom in the ring backbone.Heterocyclyls may be joined together in a fused, bridged orspiro-connected fashion. Heterocyclyls may have any degree of saturationprovided that at least one ring in the ring system is not aromatic. Theheteroatom(s) may be present in either a non-aromatic or aromatic ringin the ring system. The heterocyclyl group may have 3 to 20 ring members(i.e., the number of atoms making up the ring backbone, including carbonatoms and heteroatoms), although the present definition also covers theoccurrence of the term “heterocyclyl” where no numerical range isdesignated. The heterocyclyl group may also be a medium sizeheterocyclyl having 3 to 10 ring members. The heterocyclyl group couldalso be a heterocyclyl having 3 to 6 ring members. The heterocyclylgroup may be designated as “3-6 membered heterocyclyl” or similardesignations. In preferred six membered monocyclic heterocyclyls, theheteroatom(s) are selected from one up to three of 0, N or S, and inpreferred five membered monocyclic heterocyclyls, the heteroatom(s) areselected from one or two heteroatoms selected from O, N, or S. Examplesof heterocyclyl rings include, but are not limited to, azepinyl,acridinyl, carbazolyl, cinnolinyl, dioxolanyl, imidazolinyl,imidazolidinyl, morpholinyl, oxiranyl, oxepanyl, thiepanyl, piperidinyl,piperazinyl, dioxopiperazinyl, pyrrolidinyl, pyrrolidonyl,pyrrolidionyl, 4-piperidonyl, pyrazolinyl, pyrazolidinyl, 1,3-dioxinyl,1,3-dioxanyl, 1,4-dioxinyl, 1,4-dioxanyl, 1,3-oxathianyl,1,4-oxathiinyl, 1,4-oxathianyl, 2H-1,2-oxazinyl, trioxanyl,hexahydro-1,3,5-triazinyl, 1,3-dioxolyl, 1,3-dioxolanyl, 1,3-dithiolyl,1,3-dithiolanyl, isoxazolinyl, isoxazolidinyl, oxazolinyl, oxazolidinyl,oxazolidinonyl, thiazolinyl, thiazolidinyl, 1,3-oxathiolanyl, indolinyl,isoindolinyl, tetrahydrofuranyl, tetrahydropyranyl,tetrahydrothiophenyl, tetrahydrothiopyranyl, tetrahydro-1,4-thiazinyl,thiamorpholinyl, dihydrobenzofuranyl, benzimidazolidinyl, andtetrahydroquinoline.

An “O-carboxy” group refers to a “—OC(═O)R” group in which R is selectedfrom hydrogen, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl,C₆₋₁₀ aryl, 5-10 membered heteroaryl, and 3-10 membered heterocyclyl, asdefined herein.

A “C-carboxy” group refers to a “—C(═O)OR” group in which R is selectedfrom the group consisting of hydrogen, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10 membered heteroaryl, and3-10 membered heterocyclyl, as defined herein. A non-limiting exampleincludes carboxyl (i.e., —C(═O)OH).

A “sulfonyl” group refers to an “—SO₂R” group in which R is selectedfrom hydrogen, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl,C₆₋₁₀ aryl, 5-10 membered heteroaryl, and 3-10 membered heterocyclyl, asdefined herein.

A “sulfino” group refers to a “—S(═O)OH” group.

A “S-sulfonamido” group refers to a “—SO₂NR_(A)R_(B)” group in whichR_(A) and R_(B) are each independently selected from hydrogen, C₁₋₆alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10membered heteroaryl, and 3-10 membered heterocyclyl, as defined herein.

An “N-sulfonamido” group refers to a “—N(R_(A))SO₂R_(B)” group in whichR_(A) and R_(B) are each independently selected from hydrogen, C₁₋₆alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10membered heteroaryl, and 3-10 membered heterocyclyl, as defined herein.

A “C-amido” group refers to a “—C(═O)NR_(A)R_(B)” group in which R_(A)and R_(B) are each independently selected from hydrogen, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10 memberedheteroaryl, and 3-10 membered heterocyclyl, as defined herein.

An “N-amido” group refers to a “—N(R_(A))C(═O)R_(B)” group in whichR_(A) and R_(B) are each independently selected from hydrogen, C₁₋₆alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆-10 aryl, 5-10membered heteroaryl, and 3-10 membered heterocyclyl, as defined herein.

An “amino” group refers to a “—NR_(A)R_(B)” group in which R_(A) andR_(B) are each independently selected from hydrogen, C₁₋₆ alkyl, C₂₋₆alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10 memberedheteroaryl, and 3-10 membered heterocyclyl, as defined herein. Anon-limiting example includes free amino (i.e., —NH₂).

An “aminoalkyl” group refers to an amino group connected via an alkylenegroup.

An “alkoxyalkyl” group refers to an alkoxy group connected via analkylene group, such as a “C₂₋₈ alkoxyalkyl” and the like.

As used herein, a substituted group is derived from the unsubstitutedparent group in which there has been an exchange of one or more hydrogenatoms for another atom or group. Unless otherwise indicated, when agroup is deemed to be “substituted,” it is meant that the group issubstituted with one or more substituents independently selected fromC₁-C₆ alkyl, C₁-C₆ alkenyl, C₁-C₆ alkynyl, C₁-C₆ heteroalkyl, C₃-C₇carbocyclyl (optionally substituted with halo, C₁-C₆ alkyl, C₁-C₆alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy),C₃-C₇-carbocyclyl-C₁-C₆-alkyl (optionally substituted with halo, C₁-C₆alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), 3-10membered heterocyclyl (optionally substituted with halo, C₁-C₆ alkyl,C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), 3-10 memberedheterocyclyl-C₁-C₆-alkyl (optionally substituted with halo, C₁-C₆ alkyl,C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), aryl (optionallysubstituted with halo, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, andC₁-C₆ haloalkoxy), aryl(C₁-C₆)alkyl (optionally substituted with halo,C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), 5-10membered heteroaryl (optionally substituted with halo, C₁-C₆ alkyl,C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), 5-10 memberedheteroaryl(C₁-C₆)alkyl (optionally substituted with halo, C₁-C₆ alkyl,C₁-C₆ alkoxy, C₁-C₆ haloalkyl, and C₁-C₆ haloalkoxy), halo, —CN,hydroxy, C₁-C₆ alkoxy, C₁-C₆ alkoxy(C₁-C₆)alkyl (i.e., ether), aryloxy,sulfhydryl (mercapto), halo(C₁-C₆)alkyl (e.g., —CF₃), halo(C₁-C₆)alkoxy(e.g., —OCF₃), C₁-C₆ alkylthio, arylthio, amino, amino(C₁-C₆)alkyl,nitro, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido,N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, O-carboxy, acyl,cyanato, isocyanato, thiocyanato, isothiocyanato, sulfinyl, sulfonyl,—SO₃H, sulfino, —OSO₂C₁₋₄ alkyl, and oxo (═O). Wherever a group isdescribed as “optionally substituted” that group can be substituted withthe above substituents.

In some embodiments, substituted alkyl, alkenyl, or alkynyl groups aresubstituted with one or more substituents selected from the groupconsisting of halo, —CN, SO₃ ⁻, —SO₃H, —SR^(A), —OR^(A), —NR^(B)R^(C),oxo, —CONR^(B)R^(C), —SO₂NR^(B)R^(C), —COOH, and —COOR^(B), where R^(A),R^(B) and R^(C) are each independently selected from H, alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substitutedalkynyl, aryl, and substituted aryl.

Compounds described herein can be represented as several mesomericforms. Where a single structure is drawn, any of the relevant mesomericforms are intended. The coumarin compounds described herein arerepresented by a single structure but can equally be shown as any of therelated mesomeric forms. Exemplary mesomeric structures are shown belowfor Formula (I):

In each instance where a single mesomeric form of a compound describedherein is shown, the alternative mesomeric forms are equallycontemplated.

As understood by one of ordinary skill in the art, a compound describedherein may exist in ionized form, e.g., —CO₂ ⁻ or —SO₃ ⁻. If a compoundcontains a positively or negatively charged substituent group, forexample, SO₃ ⁻, it may also contain a negatively or positively chargedcounterion such that the compound as a whole is neutral. In otheraspects, the compound may exist in a salt form, where the counterion isprovided by a conjugate acid or base.

It is to be understood that certain radical naming conventions caninclude either a mono-radical or a di-radical, depending on the context.For example, where a substituent requires two points of attachment tothe rest of the molecule, it is understood that the substituent is adi-radical. For example, a substituent identified as alkyl that requirestwo points of attachment includes di-radicals such as —CH₂—, —CH₂CH₂—,—CH₂CH(CH₃)CH₂—, and the like. Other radical naming conventions clearlyindicate that the radical is a di-radical such as “alkylene” or“alkenylene.”

When two “adjacent” R groups are said to form a ring “together with theatom to which they are attached,” it is meant that the collective unitof the atoms, intervening bonds, and the two R groups are the recitedring. For example, when the following substructure is present:

and R¹ and R² are defined as selected from the group consisting ofhydrogen and alkyl, or R¹ and R² together with the atoms to which theyare attached form an aryl or carbocyclyl, it is meant that R¹ and R² canbe selected from hydrogen or alkyl, or alternatively, the substructurehas structure:

where A is an aryl ring or a carbocyclyl containing the depicted doublebond.

Labeled Nucleotides

According to an aspect of the disclosure, there are provided dyecompounds suitable for attachment to substrate moieties, particularlycomprising linker groups to enable attachment to substrate moieties.Substrate moieties can be virtually any molecule or substance to whichthe dyes of the disclosure can be conjugated, and, by way ofnon-limiting example, may include nucleosides, nucleotides,polynucleotides, carbohydrates, ligands, particles, solid surfaces,organic and inorganic polymers, chromosomes, nuclei, living cells, andcombinations or assemblages thereof. The dyes can be conjugated by anoptional linker by a variety of means including hydrophobic attraction,ionic attraction, and covalent attachment. In some aspects, the dyes areconjugated to the substrate by covalent attachment. More particularly,the covalent attachment is by means of a linker group. In someinstances, such labeled nucleotides are also referred to as “modifiednucleotides.”

The present disclosure further provides conjugates of nucleosides andnucleotides labeled with one or more of the dyes set forth herein(modified nucleotides). Labeled nucleosides and nucleotides are usefulfor labeling polynucleotides formed by enzymatic synthesis, such as, byway of non-limiting example, in PCR amplification, isothermalamplification, solid phase amplification, polynucleotide sequencing(e.g., solid phase sequencing), nick translation reactions and the like.

The attachment to the biomolecules may be via the R, R¹, R², R³, R⁴, R⁵,or X position of the compound of Formula (I). In some aspects, theconnection is via the R³ or R⁵ group of Formula (I). In someembodiments, the substituent group is a carboxyl or substituted alkyl,for example, alkyl substituted with —CO₂H or an activated form ofcarboxyl group, for example, an amide or ester, which may be used forattachment to the amino or hydroxyl group of the biomolecules. The term“activated ester” as used herein, refers to a carboxyl group derivativewhich is capable of reacting in mild conditions, for example, with acompound containing an amino group. Non-limiting examples of activatedesters include but not limited to p-nitrophenyl, pentafluorophenyl andsuccinimido esters.

In some embodiments, the dye compounds may be covalently attached tooligonucleotides or nucleotides via the nucleotide base. For example,the labeled nucleotide or oligonucleotide may have the label attached tothe C5 position of a pyrimidine base or the C7 position of a 7-deazapurine base through a linker moiety. The labeled nucleotide oroligonucleotide may also have a 3′-OH blocking group covalently attachedto the ribose or deoxyribose sugar of the nucleotide.

A particular useful application of the new fluorescent dyes as describedherein is for labeling biomolecules, for example, nucleotides oroligonucleotides. Some embodiments of the present application aredirected to a nucleotide or oligonucleotide labeled with the newfluorescent compounds as described herein.

Linkers

The dye compounds as disclosed herein may include a reactive linkergroup at one of the substituent positions for covalent attachment of thecompound to a substrate or another molecule. Reactive linking groups aremoieties capable of forming a bond (e.g., a covalent or non-covalentbond), in particular a covalent bond. In a particular embodiment thelinker may be a cleavable linker. Use of the term “cleavable linker” isnot meant to imply that the whole linker is required to be removed. Thecleavage site can be located at a position on the linker that ensuresthat part of the linker remains attached to the dye and/or substratemoiety after cleavage. Cleavable linkers may be, by way of non-limitingexample, electrophilically cleavable linkers, nucleophilically cleavablelinkers, photocleavable linkers, cleavable under reductive conditions(for example disulfide or azide containing linkers), oxidativeconditions, cleavable via use of safety-catch linkers and cleavable byelimination mechanisms. The use of a cleavable linker to attach the dyecompound to a substrate moiety ensures that the label can, if required,be removed after detection, avoiding any interfering signal indownstream steps.

Useful linker groups may be found in PCT Publication No. WO2004/018493(herein incorporated by reference), examples of which include linkersthat may be cleaved using water-soluble phosphines or water-solubletransition metal catalysts formed from a transition metal and at leastpartially water-soluble ligands. In aqueous solution the latter form atleast partially water-soluble transition metal complexes. Such cleavablelinkers can be used to connect bases of nucleotides to labels such asthe dyes set forth herein.

Particular linkers include those disclosed in PCT Publication No.WO2004/018493 (herein incorporated by reference) such as those thatinclude moieties of the formulae:

(wherein X is selected from the group comprising O, S, NH and NQ whereinQ is a C1-10 substituted or unsubstituted alkyl group, Y is selectedfrom the group comprising O, S, NH and N(allyl), T is hydrogen or aC₁-C₁₀ substituted or unsubstituted alkyl group and * indicates wherethe moiety is connected to the remainder of the nucleotide ornucleoside). In some aspects, the linkers connect the bases ofnucleotides to labels such as, for example, the dye compounds describedherein.

Additional examples of linkers include those disclosed in U.S.Publication Nos. 2016/0040225 and 2019/0017111 (herein incorporated byreference), such as those include moieties of the formulae:

The linker moieties illustrated herein may comprise the whole or partiallinker structure between the nucleotides/nucleosides and the labels.

In particular embodiments, the length of the linker between afluorescent dye (fluorophore) and a guanine base can be altered, forexample, by introducing a polyethylene glycol spacer group, therebyincreasing the fluorescence intensity compared to the same fluorophoreattached to the guanine base through other linkages known in the art.Exemplary linkers and their properties are set forth in PCT PublicationNo. WO2007020457 (herein incorporated by reference). The design oflinkers, and especially their increased length, can allow improvementsin the brightness of fluorophores attached to the guanine bases ofguanosine nucleotides when incorporated into polynucleotides such asDNA. Thus, when the dye is for use in any method of analysis whichrequires detection of a fluorescent dye label attached to aguanine-containing nucleotide, it is advantageous if the linkercomprises a spacer group of formula —((CH₂)₂O)_(n)—, wherein n is aninteger between 2 and 50, as described in WO 2007/020457.

Nucleosides and nucleotides may be labeled at sites on the sugar ornucleobase. As known in the art, a “nucleotide” consists of anitrogenous base, a sugar, and one or more phosphate groups. In RNA, thesugar is ribose and in DNA is a deoxyribose, i.e., a sugar lacking ahydroxyl group that is present in ribose. The nitrogenous base is aderivative of purine or pyrimidine. The purines are adenine (A) andguanine (G), and the pyrimidines are cytosine (C) and thymine (T) or inthe context of RNA, uracil (U). The C-1 atom of deoxyribose is bonded toN-1 of a pyrimidine or N-9 of a purine. A nucleotide is also a phosphateester of a nucleoside, with esterification occurring on the hydroxylgroup attached to the C-3 or C-5 of the sugar. Nucleotides are usuallymono, di- or triphosphates.

A “nucleoside” is structurally similar to a nucleotide but is missingthe phosphate moieties. An example of a nucleoside analog would be onein which the label is linked to the base and there is no phosphate groupattached to the sugar molecule.

Although the base is usually referred to as a purine or pyrimidine, theskilled person will appreciate that derivatives and analogues areavailable which do not alter the capability of the nucleotide ornucleoside to undergo Watson-Crick base pairing. “Derivative” or“analogue” means a compound or molecule whose core structure is the sameas, or closely resembles that of a parent compound but which has achemical or physical modification, such as, for example, a different oradditional side group, which allows the derivative nucleotide ornucleoside to be linked to another molecule. For example, the base maybe a deazapurine. In particular embodiments, the derivatives should becapable of undergoing Watson-Crick pairing. “Derivative” and “analogue”also include, for example, a synthetic nucleotide or nucleosidederivative having modified base moieties and/or modified sugar moieties.Such derivatives and analogues are discussed in, for example, Scheit,Nucleotide analogs (John Wiley & Son, 1980) and Uhlman et al., ChemicalReviews 90:543-584, 1990. Nucleotide analogues can also comprisemodified phosphodiester linkages including phosphorothioate,phosphorodithioate, alkyl-phosphonate, phosphoranilidate,phosphoramidate linkages and the like.

A dye may be attached to any position on the nucleotide base, forexample, through a linker. In particular embodiments, Watson-Crick basepairing can still be carried out for the resulting analog. Particularnucleobase labeling sites include the C₅ position of a pyrimidine baseor the C7 position of a 7-deaza purine base. As described above a linkergroup may be used to covalently attach a dye to the nucleoside ornucleotide.

In particular embodiments the labeled nucleoside or nucleotide may beenzymatically incorporable and enzymatically extendable. Accordingly, alinker moiety may be of sufficient length to connect the nucleotide tothe compound such that the compound does not significantly interferewith the overall binding and recognition of the nucleotide by a nucleicacid replication enzyme. Thus, the linker can also comprise a spacerunit. The spacer distances, for example, the nucleotide base from acleavage site or label.

Nucleosides or nucleotides labeled with the dyes described herein mayhave the formula:

where Dye is a dye compound; B is a nucleobase, such as, for exampleuracil, thymine, cytosine, adenine, guanine and the like; L is anoptional linker group which may or may not be present; R′ can be H,monophosphate, diphosphate, triphosphate, thiophosphate, a phosphateester analog, —O— attached to a reactive phosphorous containing group,or —O— protected by a blocking group; R″ can be H, OH, aphosphoramidite, or a 3′-OH blocking group, and R′″ is H or OH. Where R″is phosphoramidite, R′ is an acid-cleavable hydroxyl protecting groupwhich allows subsequent monomer coupling under automated synthesisconditions.

In a particular embodiment, the blocking group is separate andindependent of the dye compound, i.e., not attached to it.Alternatively, the dye may comprise all or part of the 3′-OH blockinggroup. Thus R″ can be a 3′-OH blocking group which may or may notcomprise the dye compound.

In yet another alternative embodiment, there is no blocking group on the3′ carbon of the pentose sugar and the dye (or dye and linker construct)attached to the base, for example, can be of a size or structuresufficient to act as a block to the incorporation of a furthernucleotide. Thus, the block can be due to steric hindrance or can be dueto a combination of size, charge and structure, whether or not the dyeis attached to the 3′ position of the sugar.

In still yet another alternative embodiment, the blocking group ispresent on the 2′ or 4′ carbon of the pentose sugar and can be of a sizeor structure sufficient to act as a block to the incorporation of afurther nucleotide.

The use of a blocking group allows polymerization to be controlled, suchas by stopping extension when a modified nucleotide is incorporated. Ifthe blocking effect is reversible, for example, by way of non-limitingexample by changing chemical conditions or by removal of a chemicalblock, extension can be stopped at certain points and then allowed tocontinue.

In another particular embodiment, a 3′-OH blocking group will comprise amoiety disclosed in WO2004/018497 and WO2014/139596, which are herebyincorporated by references. For example the blocking group may beazidomethyl (—CH₂N₃) or substituted azidomethyl (e.g., —CH(CHF₂)N₃ orCH(CH₂F)N₃), or allyl.

In a particular embodiment, the linker (between dye and nucleotide) andblocking group are both present and are separate moieties. In particularembodiments, the linker and blocking group are both cleavable undersubstantially similar conditions. Thus, deprotection and deblockingprocesses may be more efficient because only a single treatment will berequired to remove both the dye compound and the blocking group.However, in some embodiments a linker and blocking group need not becleavable under similar conditions, instead being individually cleavableunder distinct conditions.

The disclosure also encompasses polynucleotides incorporating dyecompounds. Such polynucleotides may be DNA or RNA comprised respectivelyof deoxyribonucleotides or ribonucleotides joined in phosphodiesterlinkage. Polynucleotides may comprise naturally occurring nucleotides,non-naturally occurring (or modified) nucleotides other than the labelednucleotides described herein or any combination thereof, in combinationwith at least one modified nucleotide (e.g., labeled with a dyecompound) as set forth herein. Polynucleotides according to thedisclosure may also include non-natural backbone linkages and/ornon-nucleotide chemical modifications. Chimeric structures comprised ofmixtures of ribonucleotides and deoxyribonucleotides comprising at leastone labeled nucleotide are also contemplated.

Non-limiting exemplary labeled nucleotides as described herein include:

wherein L represents a linker and R represents a sugar residue asdescribed above.

In some embodiments, non-limiting exemplary fluorescent dye conjugatesare shown below:

Kits

The present disclosure also provides kits including modified nucleosidesand/or nucleotides labeled with dyes. Such kits will generally includeat least one modified nucleotide or nucleoside labeled with a dye setforth herein together with at least one further component. The furthercomponent(s) may be one or more of the components identified in a methodset forth herein or in the Examples section below. Some non-limitingexamples of components that can be combined into a kit of the presentdisclosure are set forth below.

In a particular embodiment, a kit can include at least one modifiednucleotide or nucleoside labeled with a dye set forth herein togetherwith modified or unmodified nucleotides or nucleosides. For example,modified nucleotides labeled with dyes according to the disclosure maybe supplied in combination with unlabeled or native nucleotides, and/orwith fluorescently labeled nucleotides or any combination thereof.Accordingly, the kits may comprise modified nucleotides labeled withdyes according to the disclosure and modified nucleotides labeled withother, for example, prior art dye compounds. Combinations of nucleotidesmay be provided as separate individual components (e.g., one nucleotidetype per vessel or tube) or as nucleotide mixtures (e.g., two or morenucleotides mixed in the same vessel or tube).

Where kits comprise a plurality, particularly two, or three, or moreparticularly four, modified nucleotides labeled with a dye compound, thedifferent nucleotides may be labeled with different dye compounds, orone may be dark, with no dye compounds. Where the different nucleotidesare labeled with different dye compounds, it is a feature of the kitsthat the dye compounds are spectrally distinguishable fluorescent dyes.As used herein, the term “spectrally distinguishable fluorescent dyes”refers to fluorescent dyes that emit fluorescent energy at wavelengthsthat can be distinguished by fluorescent detection equipment (forexample, a commercial capillary-based DNA sequencing platform) when twoor more such dyes are present in one sample. When two modifiednucleotides labeled with fluorescent dye compounds are supplied in kitform, it is a feature of some embodiments that the spectrallydistinguishable fluorescent dyes can be excited at the same wavelength,such as, for example by the same laser. When four modified nucleotideslabeled with fluorescent dye compounds are supplied in kit form, it is afeature of some embodiments that two of the spectrally distinguishablefluorescent dyes can both be excited at one wavelength and the other twospectrally distinguishable dyes can both be excited at anotherwavelength. Particular excitation wavelengths are 488 nm and 532 nm.

In one embodiment, a kit includes a modified nucleotide labeled with acompound of the present disclosure and a second modified nucleotidelabeled with a second dye wherein the dyes have a difference inabsorbance maximum of at least 10 nm, particularly 20 nm to 50 nm. Moreparticularly, the two dye compounds have Stokes shifts of between 15-40nm where “Stokes shift” is the distance between the peak absorption andpeak emission wavelengths.

In a further embodiment, a kit can further include two other modifiednucleotides labeled with fluorescent dyes wherein the dyes are excitedby the same laser at 532 nm. The dyes can have a difference inabsorbance maximum of at least 10 nm, particularly 20 nm to 50 nm. Moreparticularly the two dye compounds can have Stokes shifts of between20-40 nm. Particular dyes which are spectrally distinguishable from dyesof the present disclosure and which meet the above criteria arepolymethine analogues as described in U.S. Pat. No. 5,268,486 (forexample Cy3) or WO 0226891 (Alexa 532; Molecular Probes A20106) orunsymmetrical polymethines as disclosed in U.S. Pat. No. 6,924,372, eachof which is incorporated herein by reference. Alternative dyes includerhodamine analogues, for example tetramethyl rhodamine and analoguesthereof.

In an alternative embodiment, the kits of the disclosure may containnucleotides where the same base is labeled with two different compounds.A first nucleotide may be labeled with a compound of the disclosure. Asecond nucleotide may be labeled with a spectrally distinct compound,for example a ‘green’ dye absorbing at less than 600 nm. A thirdnucleotide may be labeled as a mixture of the compound of the disclosureand the spectrally distinct compound, and the fourth nucleotide may be‘dark’ and contain no label. In simple terms, therefore, the nucleotides1-4 may be labeled ‘blue’, ‘green’, ‘blue/green’, and dark. To simplifythe instrumentation further, four nucleotides can be labeled with twodyes excited with a single laser, and thus the labeling of nucleotides1-4 may be ‘blue 1’, ‘blue 2’, ‘blue 1/blue 2’, and dark.

Nucleotides may contain two dyes of the present disclosure. A kit maycontain two or more nucleotides labeled with dyes of the disclosure.Kits may contain a further nucleotide where the nucleotide is labeledwith a dye that absorbs in the region of 520 nm to 560 nm. Kits mayfurther contain an unlabeled nucleotide.

Although kits are exemplified herein in regard to configurations havingdifferent nucleotides that are labeled with different dye compounds, itwill be understood that kits can include 2, 3, 4 or more differentnucleotides that have the same dye compound.

In particular embodiments, a kit may include a polymerase enzyme capableof catalyzing incorporation of the modified nucleotides into apolynucleotide. Other components to be included in such kits may includebuffers and the like. The modified nucleotides labeled with dyesaccording to the disclosure, and other any nucleotide componentsincluding mixtures of different nucleotides, may be provided in the kitin a concentrated form to be diluted prior to use. In such embodiments asuitable dilution buffer may also be included. Again, one or more of thecomponents identified in a method set forth herein can be included in akit of the present disclosure.

Methods of Sequencing

Modified nucleotides (or nucleosides) comprising a dye compoundaccording to the present disclosure may be used in any method ofanalysis such as method that include detection of a fluorescent labelattached to a nucleotide or nucleoside, whether on its own orincorporated into or associated with a larger molecular structure orconjugate. In this context the term “incorporated into a polynucleotide”can mean that the 5′ phosphate is joined in phosphodiester linkage tothe 3′ hydroxyl group of a second (modified or unmodified) nucleotide,which may itself form part of a longer polynucleotide chain. The 3′ endof a modified nucleotide set forth herein may or may not be joined inphosphodiester linkage to the 5′ phosphate of a further (modified orunmodified) nucleotide. Thus, in one non-limiting embodiment, thedisclosure provides a method of detecting a modified nucleotideincorporated into a polynucleotide which comprises: (a) incorporating atleast one modified nucleotide of the disclosure into a polynucleotideand (b) detecting the modified nucleotide(s) incorporated into thepolynucleotide by detecting the fluorescent signal from the dye compoundattached to said modified nucleotide(s).

This method can include: a synthetic step (a) in which one or moremodified nucleotides according to the disclosure are incorporated into apolynucleotide and a detection step (b) in which one or more modifiednucleotide(s) incorporated into the polynucleotide are detected bydetecting or quantitatively measuring their fluorescence.

Some embodiments of the present application are directed to methods ofsequencing including: (a) incorporating at least one labeled nucleotideas described herein into a polynucleotide; and (b) detecting the labelednucleotide(s) incorporated into the polynucleotide by detecting thefluorescent signal from the new fluorescent dye attached to saidmodified nucleotide(s).

In one embodiment, at least one modified nucleotide is incorporated intoa polynucleotide in the synthetic step by the action of a polymeraseenzyme. However, other methods of joining modified nucleotides topolynucleotides, such as, for example, chemical oligonucleotidesynthesis or ligation of labeled oligonucleotides to unlabeledoligonucleotides, can be used. Therefore, the term “incorporating,” whenused in reference to a nucleotide and polynucleotide, can encompasspolynucleotide synthesis by chemical methods as well as enzymaticmethods.

In a specific embodiment, a synthetic step is carried out and mayoptionally comprise incubating a template polynucleotide strand with areaction mixture comprising fluorescently labeled modified nucleotidesof the disclosure. A polymerase can also be provided under conditionswhich permit formation of a phosphodiester linkage between a free 3′hydroxyl group on a polynucleotide strand annealed to the templatepolynucleotide strand and a 5′ phosphate group on the modifiednucleotide. Thus, a synthetic step can include formation of apolynucleotide strand as directed by complementary base-pairing ofnucleotides to a template strand.

In all embodiments of the methods, the detection step may be carried outwhile the polynucleotide strand into which the labeled nucleotides areincorporated is annealed to a template strand, or after a denaturationstep in which the two strands are separated. Further steps, for examplechemical or enzymatic reaction steps or purification steps, may beincluded between the synthetic step and the detection step. Inparticular, the target strand incorporating the labeled nucleotide(s)may be isolated or purified and then processed further or used in asubsequent analysis. By way of example, target polynucleotides labeledwith modified nucleotide(s) as described herein in a synthetic step maybe subsequently used as labeled probes or primers. In other embodiments,the product of the synthetic step set forth herein may be subject tofurther reaction steps and, if desired, the product of these subsequentsteps purified or isolated.

Suitable conditions for the synthetic step will be well known to thosefamiliar with standard molecular biology techniques. In one embodiment,a synthetic step may be analogous to a standard primer extensionreaction using nucleotide precursors, including modified nucleotides asdescribed herein, to form an extended target strand complementary to thetemplate strand in the presence of a suitable polymerase enzyme. Inother embodiments, the synthetic step may itself form part of anamplification reaction producing a labeled double stranded amplificationproduct comprised of annealed complementary strands derived from copyingof the target and template polynucleotide strands. Other exemplarysynthetic steps include nick translation, strand displacementpolymerization, random primed DNA labeling, etc. A particularly usefulpolymerase enzyme for a synthetic step is one that is capable ofcatalyzing the incorporation of modified nucleotides as set forthherein. A variety of naturally occurring or modified polymerases can beused. By way of example, a thermostable polymerase can be used for asynthetic reaction that is carried out using thermocycling conditions,whereas a thermostable polymerase may not be desired for isothermalprimer extension reactions. Suitable thermostable polymerases which arecapable of incorporating the modified nucleotides according to thedisclosure include those described in WO 2005/024010 or WO06120433, eachof which is incorporated herein by reference. In synthetic reactionswhich are carried out at lower temperatures such as 37° C., polymeraseenzymes need not necessarily be thermostable polymerases, therefore thechoice of polymerase will depend on a number of factors such as reactiontemperature, pH, strand-displacing activity and the like.

In specific non-limiting embodiments, the disclosure encompasses methodsof nucleic acid sequencing, re-sequencing, whole genome sequencing,single nucleotide polymorphism scoring, any other application involvingthe detection of the modified nucleotide or nucleoside labeled with dyesset forth herein when incorporated into a polynucleotide. Any of avariety of other applications benefiting the use of polynucleotideslabeled with the modified nucleotides comprising fluorescent dyes canuse modified nucleotides or nucleosides with dyes set forth herein.

In a particular embodiment the disclosure provides use of modifiednucleotides comprising dye compounds according to the disclosure in apolynucleotide sequencing-by-synthesis reaction. Sequencing-by-synthesisgenerally involves sequential addition of one or more nucleotides oroligonucleotides to a growing polynucleotide chain in the 5′ to 3′direction using a polymerase or ligase in order to form an extendedpolynucleotide chain complementary to the template nucleic acid to besequenced. The identity of the base present in one or more of the addednucleotide(s) can be determined in a detection or “imaging” step. Theidentity of the added base may be determined after each nucleotideincorporation step. The sequence of the template may then be inferredusing conventional Watson-Crick base-pairing rules. The use of themodified nucleotides labeled with dyes set forth herein fordetermination of the identity of a single base may be useful, forexample, in the scoring of single nucleotide polymorphisms, and suchsingle base extension reactions are within the scope of this disclosure.

In an embodiment of the present disclosure, the sequence of a templatepolynucleotide is determined by detecting the incorporation of one ormore nucleotides into a nascent strand complementary to the templatepolynucleotide to be sequenced through the detection of fluorescentlabel(s) attached to the incorporated nucleotide(s). Sequencing of thetemplate polynucleotide can be primed with a suitable primer (orprepared as a hairpin construct which will contain the primer as part ofthe hairpin), and the nascent chain is extended in a stepwise manner byaddition of nucleotides to the 3′ end of the primer in apolymerase-catalyzed reaction.

In particular embodiments, each of the different nucleotidetriphosphates (A, T, G and C) may be labeled with a unique fluorophoreand also comprises a blocking group at the 3′ position to preventuncontrolled polymerization. Alternatively, one of the four nucleotidesmay be unlabeled (dark). The polymerase enzyme incorporates a nucleotideinto the nascent chain complementary to the template polynucleotide, andthe blocking group prevents further incorporation of nucleotides. Anyunincorporated nucleotides can be washed away and the fluorescent signalfrom each incorporated nucleotide can be “read” optically by suitablemeans, such as a charge-coupled device using laser excitation andsuitable emission filters. The 3′-blocking group and fluorescent dyecompounds can then be removed (deprotected) (simultaneously orsequentially) to expose the nascent chain for further nucleotideincorporation. Typically, the identity of the incorporated nucleotidewill be determined after each incorporation step, but this is notstrictly essential. Similarly, U.S. Pat. No. 5,302,509 (which isincorporated herein by reference) discloses a method to sequencepolynucleotides immobilized on a solid support.

The method, as exemplified above, utilizes the incorporation offluorescently labeled, 3′-blocked nucleotides A, G, C, and T into agrowing strand complementary to the immobilized polynucleotide, in thepresence of DNA polymerase. The polymerase incorporates a basecomplementary to the target polynucleotide but is prevented from furtheraddition by the 3′-blocking group. The label of the incorporatednucleotide can then be determined, and the blocking group removed bychemical cleavage to allow further polymerization to occur. The nucleicacid template to be sequenced in a sequencing-by-synthesis reaction maybe any polynucleotide that it is desired to sequence. The nucleic acidtemplate for a sequencing reaction will typically comprise a doublestranded region having a free 3′ hydroxyl group that serves as a primeror initiation point for the addition of further nucleotides in thesequencing reaction. The region of the template to be sequenced willoverhang this free 3′ hydroxyl group on the complementary strand. Theoverhanging region of the template to be sequenced may be singlestranded but can be double-stranded, provided that a “nick is present”on the strand complementary to the template strand to be sequenced toprovide a free 3′ OH group for initiation of the sequencing reaction. Insuch embodiments, sequencing may proceed by strand displacement. Incertain embodiments, a primer bearing the free 3′ hydroxyl group may beadded as a separate component (e.g., a short oligonucleotide) thathybridizes to a single-stranded region of the template to be sequenced.Alternatively, the primer and the template strand to be sequenced mayeach form part of a partially self-complementary nucleic acid strandcapable of forming an intra-molecular duplex, such as for example ahairpin loop structure. Hairpin polynucleotides and methods by whichthey may be attached to solid supports are disclosed in PCT PublicationNos. WO0157248 and WO2005/047301, each of which is incorporated hereinby reference. Nucleotides can be added successively to a growing primer,resulting in synthesis of a polynucleotide chain in the 5′ to 3′direction. The nature of the base which has been added may bedetermined, particularly but not necessarily after each nucleotideaddition, thus providing sequence information for the nucleic acidtemplate. Thus, a nucleotide is incorporated into a nucleic acid strand(or polynucleotide) by joining of the nucleotide to the free 3′ hydroxylgroup of the nucleic acid strand via formation of a phosphodiesterlinkage with the 5′ phosphate group of the nucleotide.

The nucleic acid template to be sequenced may be DNA or RNA, or even ahybrid molecule comprised of deoxynucleotides and ribonucleotides. Thenucleic acid template may comprise naturally occurring and/ornon-naturally occurring nucleotides and natural or non-natural backbonelinkages, provided that these do not prevent copying of the template inthe sequencing reaction.

In certain embodiments, the nucleic acid template to be sequenced may beattached to a solid support via any suitable linkage method known in theart, for example via covalent attachment. In certain embodimentstemplate polynucleotides may be attached directly to a solid support(e.g., a silica-based support). However, in other embodiments of thedisclosure the surface of the solid support may be modified in some wayso as to allow either direct covalent attachment of templatepolynucleotides, or to immobilize the template polynucleotides through ahydrogel or polyelectrolyte multilayer, which may itself benon-covalently attached to the solid support.

Arrays in which polynucleotides have been directly attached tosilica-based supports are those for example disclosed in WO00006770(incorporated herein by reference), wherein polynucleotides areimmobilized on a glass support by reaction between a pendant epoxidegroup on the glass with an internal amino group on the polynucleotide.In addition, polynucleotides can be attached to a solid support byreaction of a sulfur-based nucleophile with the solid support, forexample, as described in WO2005/047301 (incorporated herein byreference). A still further example of solid-supported templatepolynucleotides is where the template polynucleotides are attached tohydrogel supported upon silica-based or other solid supports, forexample, as described in WO00/31148, WO01/01143, WO02/12566,WO03/014392, U.S. Pat. No. 6,465,178 and WO00/53812, each of which isincorporated herein by reference.

A particular surface to which template polynucleotides may beimmobilized is a polyacrylamide hydrogel. Polyacrylamide hydrogels aredescribed in the references cited above and in WO2005/065814, which isincorporated herein by reference. Specific hydrogels that may be usedinclude those described in WO 2005/065814 and U.S. Pub. No.2014/0079923. In one embodiment, the hydrogel is PAZAM(poly(N-(5-azidoacetamidylpentyl) acrylamide-co-acrylamide)).

DNA template molecules can be attached to beads or microparticles, forexample, as described in U.S. Pat. No. 6,172,218 (which is incorporatedherein by reference). Attachment to beads or microparticles can beuseful for sequencing applications. Bead libraries can be prepared whereeach bead contains different DNA sequences. Exemplary libraries andmethods for their creation are described in Nature, 437, 376-380 (2005);Science, 309, 5741, 1728-1732 (2005), each of which is incorporatedherein by reference. Sequencing of arrays of such beads usingnucleotides set forth herein is within the scope of the disclosure.

Template(s) that are to be sequenced may form part of an “array” on asolid support, in which case the array may take any convenient form.Thus, the method of the disclosure is applicable to all types ofhigh-density arrays, including single-molecule arrays, clustered arrays,and bead arrays. Modified nucleotides labeled with dye compounds of thepresent disclosure may be used for sequencing templates on essentiallyany type of array, including but not limited to those formed byimmobilization of nucleic acid molecules on a solid support.

However, the modified nucleotides labeled with dye compounds of thedisclosure are particularly advantageous in the context of sequencing ofclustered arrays. In clustered arrays, distinct regions on the array(often referred to as sites, or features) comprise multiplepolynucleotide template molecules. Generally, the multiplepolynucleotide molecules are not individually resolvable by opticalmeans and are instead detected as an ensemble. Depending on how thearray is formed, each site on the array may comprise multiple copies ofone individual polynucleotide molecule (e.g., the site is homogenous fora particular single- or double-stranded nucleic acid species) or evenmultiple copies of a small number of different polynucleotide molecules(e.g., multiple copies of two different nucleic acid species). Clusteredarrays of nucleic acid molecules may be produced using techniquesgenerally known in the art. By way of example, WO 98/44151 andWO00/18957, each of which is incorporated herein, describe methods ofamplification of nucleic acids wherein both the template andamplification products remain immobilized on a solid support in order toform arrays comprised of clusters or “colonies” of immobilized nucleicacid molecules. The nucleic acid molecules present on the clusteredarrays prepared according to these methods are suitable templates forsequencing using the modified nucleotides labeled with dye compounds ofthe disclosure.

The modified nucleotides labeled with dye compounds of the presentdisclosure are also useful in sequencing of templates on single moleculearrays. The term “single molecule array” or “SMA” as used herein refersto a population of polynucleotide molecules, distributed (or arrayed)over a solid support, wherein the spacing of any individualpolynucleotide from all others of the population is such that it ispossible to individually resolve the individual polynucleotidemolecules. The target nucleic acid molecules immobilized onto thesurface of the solid support can thus be capable of being resolved byoptical means in some embodiments. This means that one or more distinctsignals, each representing one polynucleotide, will occur within theresolvable area of the particular imaging device used.

Single molecule detection may be achieved wherein the spacing betweenadjacent polynucleotide molecules on an array is at least 100 nm, moreparticularly at least 250 nm, still more particularly at least 300 nm,even more particularly at least 350 nm. Thus, each molecule isindividually resolvable and detectable as a single molecule fluorescentpoint, and fluorescence from said single molecule fluorescent point alsoexhibits single step photobleaching.

The terms “individually resolved” and “individual resolution” are usedherein to specify that, when visualized, it is possible to distinguishone molecule on the array from its neighboring molecules. Separationbetween individual molecules on the array will be determined, in part,by the particular technique used to resolve the individual molecules.The general features of single molecule arrays will be understood byreference to published applications WO00/06770 and WO 01/57248, each ofwhich is incorporated herein by reference. Although one use of themodified nucleotides of the disclosure is in sequencing-by-synthesisreactions, the utility of the modified nucleotides is not limited tosuch methods. In fact, the nucleotides may be used advantageously in anysequencing methodology which requires detection of fluorescent labelsattached to nucleotides incorporated into a polynucleotide.

In particular, the modified nucleotides labeled with dye compounds ofthe disclosure may be used in automated fluorescent sequencingprotocols, particularly fluorescent dye-terminator cycle sequencingbased on the chain termination sequencing method of Sanger andco-workers. Such methods generally use enzymes and cycle sequencing toincorporate fluorescently labeled dideoxynucleotides in a primerextension sequencing reaction. So-called Sanger sequencing methods, andrelated protocols (Sanger-type), utilize randomized chain terminationwith labeled dideoxynucleotides.

Thus, the present disclosure also encompasses modified nucleotideslabeled with dye compounds which are dideoxynucleotides lacking hydroxylgroups at both of the 3′ and 2′ positions, such modifieddideoxynucleotides being suitable for use in Sanger type sequencingmethods and the like.

Modified nucleotides labeled with dye compounds of the presentdisclosure incorporating 3′ blocking groups, it will be recognized, mayalso be of utility in Sanger methods and related protocols since thesame effect achieved by using modified dideoxy nucleotides may beachieved by using modified nucleotides having 3′-OH blocking groups:both prevent incorporation of subsequent nucleotides. Where nucleotidesaccording to the present disclosure, and having a 3′ blocking group areto be used in Sanger-type sequencing methods it will be appreciated thatthe dye compounds or detectable labels attached to the nucleotides neednot be connected via cleavable linkers, since in each instance where alabeled nucleotide of the disclosure is incorporated; no nucleotidesneed to be subsequently incorporated and thus the label need not beremoved from the nucleotide.

EXAMPLES

Additional embodiments are disclosed in further detail in the followingexamples, which are not in any way intended to limit the scope of theclaims.

Example 1: Compound I-1:7-(3-Carboxyazetidinyl-1)-3-(5-chloro-benzoxazol-2-yl)coumarin

3-(5-Chloro-benzoxazol-2-yl)-7-fluoro-coumarin (0.32 g, 1 mmol) and3-carboxyazetidine (0.2 g, 2 mmol) were added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 7 h at 120° C., and standing at roomtemperature for 1 h, the mixture was diluted with water (15 mL) andstirred overnight. The resulting precipitate was collected by suctionfiltration. Yield 0.25 g (63%). Purity, structure and composition of theproduct were confirmed by HPLC, NMR and LCMS. MS (DUIS): MW Calculated396.05. Found m/z: (+) 397 (M+1)⁺; (−) 395 (M−1)⁻.

Example 2. Compound I-2:7-(3-Carboxyazetidin-1-yl)-3-(benzoxazol-2-yl)coumarin

3-(Benzoxazol-2-yl)-7-fluoro-coumarin (0.56 g, 2 mmol) and3-carboxyazetidine (0.3 g, 3 mmol) is added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 9 h at 125° C. and standing at roomtemperature for 1 h, the reaction mixture was diluted with water (10 mL)and stirred overnight. The resulting precipitate was collected bysuction filtration. Yield 0.41 g (56%). Purity, structure andcomposition of the product were confirmed by HPLC, NMR and LCMS. MS(DUIS): MW Calculated 362.09. Found m/z: (+) 363 (M+1)⁺.

Example 3. Compound I-3:7-(3-Carboxyazetidin-1-yl)-3-(benzimidazol-2-yl)coumarin

3-(Benzimidazol-2-yl)-7-fluoro-coumarin (FC-2, 0.56 g, 2 mmol, 1 eq.)and 3-carboxyazetidine (AC-C4, 0.3 g, 3 mmol, 1.5 eq) were added toanhydrous dimethyl sulfoxide (DMSO, 5 mL) in round bottomed flask. Themixture was stirred for a few minutes at room temperature and then DIPEA(0.52 g, 4 mmol) was added. The mixture is stirred for 9 h at 120° C.Additional portions of 3-carboxyazetidine (0.3 g, 3 mmol) and DIPEA(0.26 g, 2 mmol) were added. After stirring at 120° C. for another 3 h,and standing at room temperature for 1 h, the reaction mixture wasdiluted with water (10 mL) and stirred overnight. The resultingprecipitate was collected by suction filtration. Yield 0.26 g (36%).Purity, structure and composition of the product were confirmed by HPLC,NMR and LCMS. MS (DUIS): MW Calculated 361.11. Found m/z: (+) 362(M+1)⁺; (−) 360 (M−1)⁻.

Example 4. Compound I-4:7-(3-Carboxyazetidin-1-yl)-3-(benzothiazol-2-yl)coumarin

3-(Benzothiazol-2-yl)-7-fluoro-coumarin (0.30 g, 1 mmol) and3-carboxyazetidine (0.2 g, 2 mmol) were added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 8 h at 120° C. and standing at roomtemperature for 1 h, the reaction mixture was diluted with water (10 mL)and was stirred overnight. The resulting precipitate is collected bysuction filtration. Yield 0.28 g (75%). Purity, structure andcomposition of the product were confirmed by HPLC, NMR and LCMS. MS(DUIS): MW Calculated 378.07. Found m/z: (+) 379 (M+1)⁺; (−) 377 (M−1)⁻.

Example 5. Compound I-5:7-(3-Carboxypyrrolidin-yl-1)-3-(benzothiazol-2-yl)coumarin

3-(Benzothiazol-2-yl)-7-fluoro-coumarin (0.30 g, 1 mmol) and3-carboxypyrrolidine (0.23 g, 2 mmol) were added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 6 h at 120° C. and standing at roomtemperature for 1 h, the reaction mixture was diluted with water (20 mL)and was stirred overnight. The resulting precipitate was collected bysuction filtration. Yield 0.31 g (80%). Purity, structure andcomposition of the product were confirmed by HPLC, NMR and LCMS. MS(DUIS): MW Calculated 392.08. Found m/z: (+) 393 (M+1)⁺; (−) 391 (M−1)⁻.

Example 6. Compound I-6:7-(4-Carboxypiperidin-1-yl)-3-(benzothiazol-2-yl)coumarin

3-(Benzothiazol-2-yl)-7-fluoro-coumarin (0.30 g, 1 mmol) andisonipecotic acid (0.26 g, 2 mmol) were added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 6 h at 120° C. and standing at roomtemperature for 1 h, the reaction mixture was diluted with water (20 mL)and was stirred overnight. The resulting precipitate was collected bysuction filtration. Yield 0.34 g (83%). Purity, structure andcomposition of the product were confirmed by HPLC, NMR and LCMS. MS(DUIS): MW Calculated 406.10 Found m/z: (+) 407 (M+1)⁺; (−) 405 (M−1)⁻.

Example 7. Compound I-7:7-(3-Carboxyazetidin-1-yl)-3-(6-sulfo-benzothiazol-2-yl)coumarin

7-(3-Carboxyazetidin-1-yl)-3-(benzothiazol-2-yl)coumarin (0.38 g, 1mmol) was added at about −5° C. to 20% fuming sulfuric acid (0.5 mL).The mixture was stirred with cooling for a few hours and then at roomtemperature for 3 h. After stirring for 1 h at 80° C. and standing atroom temperature for 1 h, the reaction mixture was diluted withanhydrous diethyl ether (10 mL) and was stirred overnight. The resultingprecipitate is collected by suction filtration. Product was purified byHPLC. Yield 0.1 g (22%). Purity, structure and composition of theproduct were confirmed by HPLC, NMR and LCMS. MS (DUIS): MW Calculated458.02. Found m/z: (+) 459 (M+1)⁺.

Example 8. Compound I-8:7-(3-Carboxyazetidin-1-yl)-3-(6-sulfamido-benzoxazol-2-yl)coumarin

3-(6-Sulfamido-benzoxazol-2-yl)-7-fluoro-coumarin (0.36 g, 1 mmol) and3-carboxyazetidine (0.3 g, 3 mmol) is added to anhydrous dimethylsulfoxide (DMSO, 5 mL) in round bottomed flask. The mixture was stirredfor a few minutes at room temperature and then DIPEA (0.52 g, 4 mmol)was added. After stirring for 9 h at 125° C. and standing at roomtemperature for 1 h, the reaction mixture was diluted with water (10 mL)and stirred overnight. The resulting precipitate was collected bysuction filtration. Yield 0.26 g (60%). Purity, structure andcomposition of the product were confirmed by HPLC, NMR and LCMS. MS(DUIS): MW Calculated 441.06. Found m/z: (+) 442 (M+1)⁺.

Example 9. Comparison of Fluorescence Intensities

Fluorescence intensities of exemplary dye solutions (at maximumexcitation wavelength 450 nm) were compared with a standard dye for thesame spectral region. The results are shown in Table 1 and demonstratesignificant advantages of the exemplary dyes for fluorescence basedanalytical applications.

TABLE 1 Spectral properties of the new fluorescent dyes disclosed in theexamples. Spectral properties in EtOH-Water 1:1 Relative Abs. maxFluorescence Fluorescence Number Structure (nm) max (nm) Intensity (%)I-1

451 499 90 I-2

446 496 70 I-3

443 496 75 I-4

449 497 94 I-5

473 512 138 I-6

463 514 98

Example 10. General Procedure for the Synthesis of Fully FunctionalNucleotide Conjugates

Coumarin fluorescent dyes disclosed herein were coupled with appropriateamino-substituted adenine (A) and cytosine (C) nucleotide derivativesA-LN3-NH₂ or C-LN3-NH₂:

After activation of carboxylic group of a dye with appropriate reagentsaccording to the following adenine exemplary scheme:

The general product for the adenine coupling is as shown below:

ffA-LN3-Dye refers to a fully functionalized A nucleotide with an LN3linker and labeled with a coumarin dye disclosed herein. The R group ineach of the structures refers to the coumarin dye moiety afterconjugation.

The dye (10 μmol) is dried by placing into a 5 mL round-bottomed flaskand is dissolved in anhydrous dimethylformamide (DMF, 1 mL) then thesolvent is distilled off in vacuo. This procedure is repeated twice. Thedried dye is dissolved in anhydrous N,N-dimethylacetamide (DMA, 0.2 mL)at room temperature. N,N,N′,N′-Tetramethyl-O—(N-succinimidyl)uroniumtetrafluoroborate (TSTU, 1.5 eq., 15 μmol, 4.5 mg) is added to the dyesolution, then DIPEA (3 eq., 30 μmol, 3.8 mg, 5.2 μL) is added viamicropipette to this solution. The reaction flask is sealed undernitrogen gas. The reaction progress is monitored by TLC (eluentAcetonitrile-Water 1:9) and HPLC. Meanwhile, a solution of theappropriate amino-substituted nucleotide derivative (A-LN3-NH₂, 20 mM,1.5 eq, 15 μmol, 0.75 mL) is concentrated in vacuo then re-dissolved inwater (20 μL). A solution of the activated dye in DMA is transferred tothe flask containing the solution of N-LN3-NH₂. More DIPEA (3 eq, 30μmol, 3.8 mg, 5.2 μL) is added along with triethylamine (1 μL). Progressof coupling is monitored hourly by TLC, HPLC, and LCMS. When thereaction is complete, triethylamine bicarbonate buffer (TEAB, 0.05 M˜3mL) is added to the reaction mixture via pipette. Initial purificationof the fully functionalized nucleotide is carried out by running thequenched reaction mixture through a DEAE-Sephadex® column to remove mostof remaining unreacted dye. For example, Sephadex is poured into anempty 25 g Biotage cartridge, solvent system TEAB/MeCN. The solutionfrom the Sephadex column is concentrated in vacuo. The remainingmaterial is redissolved in the minimum volume of water and acetonitrile,before filtering through a 20 μm Nylon filter. The filtered solution ispurified by preparative-HPLC. The composition of prepared compounds isconfirmed by LCMS.

The general product for the cytosine coupling is as shown below,following similar procedure described above.

ffC-LN3-Dye refers to a fully functionalized C nucleotide with an LN3linker and labeled with a coumarin dye disclosed herein. The R group ineach of the structures refers to the coumarin dye moiety afterconjugation.

Example 11. Preparation of Amide Derivatives of the Compounds of Formula(I)

Some additional embodiments described herein are related to amidederivatives of compounds of Formula (I) and methods of preparing thesame, the methods include converting a compound of Formula (Ia) to acompound of Formula (Ia′) through carboxylic acid activation:

and reacting the compound of Formula (Ia′) with a primary or secondaryamine of Formula (Am) to arrive at the amide derivative of Formula (Ib):

where the variables X, R, R¹, R², R³, R⁴, and n are defined herein; R′is the residual moiety of a carboxyl activating agent (such asN-hydroxysuccinimide, nitrophenol, pentafluorophenol, HOBt, BOP, PyBOP,DCC, etc.); each of R_(A) and R_(B) is independently hydrogen, C₁₋₆alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₇ carbocyclyl, C₆₋₁₀ aryl, 5-10membered heteroaryl, 3-10 membered heterocyclyl, aralkyl, heteroaralkyl,or (heterocyclyl)alkyl.

General Procedure for the Preparation of Compounds of Formula (Ib)

An appropriate dye of Formula (Ia) (0.001 mol) is dissolved in suitableanhydrous organic solvent (DMF, 1.5 mL). To this solution a carboxylactivating reagent such as TSTU, BOP or PyBOP is added. This reactionmixture is stirred at room temperature for about 20 min and thenappropriate amine derivatives is added. The reaction mixture is stirredovernight, filtered and excess of the activation reagent is quenchedwith 0.1M TEAB solution in water. Solvents is evaporated in vacuum andthe residue is re-dissolved in TEAB solution and purified by HPLC.

Example 12. Two-Channel Sequencing Applications

The efficiency of the A nucleotides labeled with the new dyes describedherein in sequencing application was demonstrated in the two-channeldetection method. With respect to the two-channel methods describedherein, nucleic acids can be sequenced utilizing methods and systemsdescribed in U.S. Patent Application No. 2013/0079232, the disclosure ofwhich is incorporated herein by reference in its entirety.

In the two-channel detection, a nucleic acid can be sequenced byproviding a first nucleotide type that is detected in a first channel, asecond nucleotide type that is detected in a second channel, a thirdnucleotide type that is detected in both—the first and the secondchannel and a fourth nucleotide type that lacks a label that is not, orminimally, detected in either channel. The scatterplots were generatedby RTA2.0.93 analysis of an experiment. The scatterplots illustrated inFIG. 1 through FIG. 3 were at cycle 5 of each of the 26 cycle runs.

FIG. 1 illustrates the scatterplot of a fully functionalized nucleotides(ffN) mixture containing: A-I-4 (0.5 μM), A-NR550S0 (1.5 μM), C-NR440 (2μM), dark G (2 μM) and T-AF550POPOS0 (2 μM) in incorporation buffer withPo1812. Blue exposure (Chanel 1) 500 ms, Green exposure (Chanel 2) 1000ms; Scanned in Scanning mix).

FIG. 2 illustrates the scatterplot of a fully functionalized nucleotides(ffN) mixture containing: A-I-5 (1 μM), A-NR550S0 (1 μM), C-NR440 (2μM), dark G (2 μM) and T-AF550POPOS0 (2 μM) in incorporation buffer withPo1812. Blue exposure (Chanel 1) 500 ms, Green exposure (Chanel 2) 1000ms; Scanned in Scanning mix.

FIG. 3 illustrates the scatterplot of a fully functionalized nucleotides(ffN) mixture containing: A-I-6 (1 μM), A-NR550S0 (1 μM), C-NR440 (2μM), dark G (2 μM) and T-AF550POPOS0 (2 μM) in incorporation buffer withPo1812. Blue exposure (Chanel 1) 500 ms, Green exposure (Chanel 2) 1000ms; Scanned in Scanning mix.

In each of FIGS. 1-3, “G” nucleotide is unlabeled and shown as the lowerleft cloud (“dark G”). The signal from a mixture of “A” nucleotidelabeled by the new dyes described herein and a green dye (NR550S0) isshown as the upper right cloud in FIGS. 1-3 respectively. The signalfrom the “T” nucleotide labelled with dye AF550POPOS0 is indicated bythe upper left cloud, and signal from “C” nucleotide labelled by dyeNR440 is indicated by the lower right cloud. The X-axis shows the signalintensity for one (Blue) channel and the Y-axis shows the signalintensity for the other (Green) channel. The chemical structures ofNR440, AF550POPOS0, and NR550S0 are disclosed in PCT Publication Nos.WO2018060482A1, WO2017051201A1, and WO2014135221A1 respectively, all ofwhich are incorporated by references.

FIGS. 1-3 each shows that the fully functional A-nucleotide conjugateslabelled with the new dye described herein provides sufficient signalintensities and great cloud separation.

What is claimed is:
 1. A compound of Formula (I), a salt or a mesomericform thereof:

wherein: X is O, S, Se, or NR^(a), wherein R^(n) is H, C₁₋₆ alkyl, orC₆₋₁₀ aryl; ring A is

R, R¹, R², and R⁴ are each independently H, halo, —CN, —CO₂H, amino,—OH, C-amido, N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b), optionallysubstituted alkyl, optionally substituted alkenyl, optionallysubstituted alkynyl, optionally substituted alkoxy, optionallysubstituted aminoalkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl; each R³ is independently —CO₂H,—(CH₂)_(p)—CO₂R^(c), —SO₃H, or C₁₋₄ alkyl substituted with —CO₂H or—SO₃H; wherein p is 1, 2, 3 or 4; each R⁵ is independently halo, —CN,—CO₂R^(f), amino, —OH, C-amido, N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b),optionally substituted alkyl, optionally substituted alkenyl, optionallysubstituted alkynyl, optionally substituted alkoxy, optionallysubstituted aminoalkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl; each R^(a) and R^(b) is independently H oroptionally substituted C₁₋₆ alkyl; each R^(c), and R^(f) isindependently H, optionally substituted C₁₋₆ alkyl, optionallysubstituted carbocyclyl, optionally substituted heterocyclyl, optionallysubstituted aryl, or optionally substituted heteroaryl; m is 0, 1, 2, 3,or 4; and n is 1, 2 or
 3. 2. The compound of claim 1, wherein X is O orS.
 3. The compound of claim 1, wherein each of R and R¹ is independentlyH, halo, or C₁₋₆alkyl.
 4. The compound of claim 3, wherein R is H. 5.The compound of claim 3, wherein R¹ is H.
 6. The compound claim 1,wherein R² is H, —SO₃H, optionally substituted alkyl, or C₁₋₄ alkyloptionally substituted with —CO₂H or —SO₃H.
 7. The compound of claim 6,wherein R² is H or —SO₃H.
 8. The compound of claim 1, wherein R⁴ is H,—SO₃H, optionally substituted alkyl, or C₁₋₄ alkyl optionallysubstituted with —CO₂H or —SO₃H.
 9. The compound of claim 8, wherein R⁴is H or —SO₃H.
 10. The compound of claim 1, wherein n is 1 and R³ is—CO₂H or —(CH₂)_(p)—CO₂R^(c).
 11. The compound of claim 1, wherein eachR⁵ is halo, —CN, —CO₂H, —SO₃H, —SO₂NR^(a)R^(b), or optionallysubstituted C₁₋₆ alkyl.
 12. The compound of claim 11, wherein R⁵ is—CO₂H, —SO₃H, —SO₂NH₂, or C₁₋₆ alkyl substituted with —CO₂H, —SO₃H, or—SO₂NH₂.
 13. The compound of claim 1, wherein X is O, S, or NH; each R,R¹, R², and R⁴ is H; n is 1; R³ is —CO₂H or —(CH₂)_(p)—CO₂R^(c); m is 0or 1; and R⁵ is halo, —CO₂H, —SO₃H, —SO₂NH₂, or C₁₋₆ alkyl substitutedwith —SO₃H or —SO₂NH₂.
 14. The compound of claim 1, selected from thegroup consisting of:

and salts and mesomeric forms thereof.
 15. A nucleotide oroligonucleotide labeled with a compound according to claim
 1. 16. Thelabeled nucleotide or oligonucleotide according to claim 15, wherein thecompound is attached the nucleotide or oligonucleotide via R³ of Formula(I), and wherein R³ of Formula (I) is —CO₂H or —(CH₂)_(p)—CO₂H and theattachment forms an amide using the —CO₂H group.
 17. The labelednucleotide or oligonucleotide according to claim 15, wherein thecompound is attached the nucleotide or oligonucleotide via R⁵ of Formula(I), and wherein R⁵ of Formula (I) is —CO₂H and the attachment forms anamide using the —CO₂H group.
 18. The labeled nucleotide oroligonucleotide of claim 15, wherein the compound is attached to the C5position of a pyrimidine base or the C7 position of a 7-deaza purinebase through a linker moiety.
 19. The labeled nucleotide oroligonucleotide according to claim 15, further comprising a 3′ OHblocking group covalently attached to the ribose or deoxyribose sugar ofthe nucleotide.
 20. A kit comprising a first labeled nucleotideaccording to claim 15 and a second labeled nucleotide.
 21. The kit ofclaim 20, wherein the second labeled nucleotide is labeled with adifferent compound than the first labeled nucleotide.
 22. The kit ofclaim 21, wherein the first and second labeled nucleotides are excitableusing a single laser wavelength.
 23. The kit of claim 21, furthercomprising a third nucleotide and a fourth nucleotide, wherein each ofthe second, third, and fourth nucleotides is labeled with a differentcompound, wherein each label has a distinct absorbance maximum that isdistinguishable from the other labels.
 24. The kit of claim 20, whereinthe kit comprises four nucleotides, wherein a first of the fournucleotides is a labeled nucleotide according to claim 15, a second ofthe four nucleotides carries a second label, a third nucleotide carriesa third label, and a fourth nucleotide is unlabeled (dark).
 25. The kitof claim 20, wherein the kit comprises four nucleotides, wherein a firstof the four nucleotides is a labeled nucleotide according to claim 15, asecond of the four nucleotides carries a second label, a thirdnucleotide carries a mixture of two labels, and a fourth nucleotide isunlabeled (dark).
 26. A method of sequencing comprising incorporating alabeled nucleotide according to claim 15 in a sequencing assay.
 27. Amethod of synthesizing a compound of claim 1, comprising reacting acompound of Formula (II) with an optionally substituted cyclic amine ofFormula (III):

wherein X is O, S, Se, or NR^(n), wherein R^(n) is H, C₁₋₆ alkyl, orC₆₋₁₀ aryl; ring A is

R, R¹, R², and R⁴ are each independently H, halo, —CN, —CO₂H, amino,—OH, C-amido, N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b), optionallysubstituted alkyl, optionally substituted alkenyl, optionallysubstituted alkynyl, optionally substituted alkoxy, optionallysubstituted aminoalkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl; each R³ is independently —CO₂H,—(CH₂)_(p)—CO₂R^(c), —SO₃H, or C₁₋₄ alkyl substituted with —CO₂H or—SO₃H; wherein p is 1, 2, 3 or 4; each R⁵ is independently halo, —CN,—CO₂R^(f), amino, —OH, C-amido, N-amido, —NO₂, —SO₃H, —SO₂NR^(a)R^(b),optionally substituted alkyl, optionally substituted alkenyl, optionallysubstituted alkynyl, optionally substituted alkoxy, optionallysubstituted aminoalkyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, or optionallysubstituted heteroaryl; each R^(a) and R^(b) is independently H oroptionally substituted C₁₋₆ alkyl; each R^(c), and R^(f) isindependently H, optionally substituted C₁₋₆ alkyl, optionallysubstituted carbocyclyl, optionally substituted heterocyclyl, optionallysubstituted aryl, or optionally substituted heteroaryl; m is 0, 1, 2, 3,or 4; and n is 1, 2 or 3.